OACore JVM Sizing, Check and Increase JVM Size and Count

To check if there are issues with sizing

cd $LOG_HOME/ora/10.1.3/opmn/
ls -ltr default_group~oacore*

grep 'Full GC' default_group~oacore* | wc -l
grep 'Unloading class' default_group~oacore* | grep 'Full GC' | wc -l

If you see there are multiple cases when Full GC is happening then,  JVM sizing is not proper.

Take the following actions for this:
1. Increase the Number of OACore JVMs
2. Increase the JVM Heap Size

Increase the JVM Heap Size

Default Value is  “-Xmx512M -Xms128M”.

Check current Size:
./adoacorectl.sh status | grep "OC4J:oacore" | awk -F"|" '{print $3}' | while read L ; do ps -fp $L | grep -v PID ; done | awk -F"-X" '{print $2 $3}'
mx512M ms128M

Change Memory Parameters

I would start with  “-Xmx2048M -Xms1024M” set up.
To change the memory parameters, edit $CONTEXT_FILE and change the following line:

[applmgr@funebs121 scripts]$ grep s_oacore_jvm_start_options $CONTEXT_FILE
                        <oacore_jvm_start_options oa_var="s_oacore_jvm_start_options">-server -verbose:gc -Xmx2048M -Xms1024M -XX:MaxPermSize=160M -XX:NewRatio=2  -XX:+PrintGCTimeStamps -XX:+UseTLAB -XX:+UseParallelGC  -XX:ParallelGCThreads=2  -Dcom.sun.management.jmxremote 

Run autoconfig:

And restart OACORE component:
./adopmnctl.sh stopall
./adopmnctl.sh startall

-Xmx256M -> this mean maximum heap size is 256MB

-Xms64M  -> this mean initial heap size is 128MB

-XX:MaxPermSize -> specifies the the maximum size for the permanent generation heap

Increase the Number of OACore JVMs

change opmn.xml in $ORA_CONFIG_HOME/10.1.3/opmn/conf directory.

You need to change the following tag in opmn.xml under  below tag
<process-type id="oacore" module-id="OC4J" status="enabled" working-dir="$ORACLE_HOME/j2ee/home">

< process-set id="default_group" numprocs="1">

In addition to that, 

Change the $CONTEXT_FILE to reflect the change and protect it against future autoconfig.

You need the change the following tag in context file;

<oacore_nprocs oa_var="s_oacore_nprocs">1 

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